Patient support apparatus

ABSTRACT

The present application relates to a patient support apparatus for a radiotherapy device. The patient support apparatus comprises a support surface and abase. The patient support apparatus also comprises a first connection assembly connecting the surface and the base, the first connection assembly being connected to the surface at a first connection point, wherein the first connection assembly is coupled to a first driving mechanism configured to effect translation of the first connection point in a substantially vertical direction. The patient support apparatus also comprises a second connection assembly connecting the surface and the base, the second connection assembly being connected to the surface at a second connection point, wherein the second connection assembly is coupled to a second driving mechanism configured to effect translation of the second connection point in the substantially vertical direction. The patient support apparatus also comprises a third connection assembly connecting the surface and the base, the third connection assembly being connected to the surface at a third connection point, wherein the third connection assembly is coupled to a third driving mechanism configured to effect translation of the third connection point in the substantially vertical direction, wherein the third connection assembly further comprises a pivot joint at the third connection point configured to enable relative rotation between the surface and the base. The first, second and third driving mechanisms are configured to be independently driven to provide rotation and vertical translation of the surface with respect to the base.

This disclosure relates generally to an apparatus for supporting a patient, and in particular to an apparatus for providing pitch, roll and/or vertical translation of the surface of the apparatus.

BACKGROUND

Radiotherapy uses ionising radiation to treat a human or animal body. In particular, radiotherapy is commonly used to treat tumours within the human or animal body. In such treatments, cells forming part of the tumour are irradiated by ionising radiation in order to destroy or damage them. However, in order to apply a prescribed dose of ionising radiation to a target location or target region, such as a tumour, the ionising radiation will typically also pass through healthy tissue of the human or animal body. Therefore, radiotherapy has the desirable consequence of irradiating and damaging a target region, but can also have the undesirable consequence of irradiating and damaging healthy tissue. In radiotherapy treatment, it is desirable to align the dose received with the target region to minimise the dose received by healthy tissue.

During a radiotherapy treatment session, a patient lies on the patient support surface of a patient support apparatus, which may also be referred to as a couch. The patient support surface supports the patient while they are exposed to a source of ionizing radiation as part of the treatment process. It is beneficial for the patient support surface to be adjustable for a number of reasons.

Image-guided radiotherapy (IGRT) treatment plans are created based on 3D reference images of the patient's anatomy. Just before treatment is to commence, an image may be taken of the patient positioned on the patient support apparatus, and any offset between the treatment plan reference image and the patient's anatomy may be corrected by adjusting the patient support apparatus. By ensuring alignment of the patient's anatomy on the day of treatment with their anatomy as depicted in the treatment plan reference image, the efficacy of the radiotherapy treatment plan is improved.

For radiotherapy devices with bores, such as MR-linacs, it is desirable to be able to move the support surface into and out of the bore to enable the patient to easily mount the support surface. This is typically accomplished via movement of the support surface in a direction parallel with a longitudinal axis of the support surface. It is also desirable to be able to adjust the height of the patient support surface, for example in order to enable patients to more easily position themselves on the couch. The lowest possible height of the couch is sometimes referred to as the ‘hop-on’ height, and it is desirable to reduce the hop-on height to better enable patients to position themselves on the couch. In part for this reason, it is desirable to keep the height of any mechanism for adjusting the position of the surface of the couch as compact as possible so as to avoid negatively impacting the hop-on height.

Various couch rotation, translation, and height adjustment mechanisms have been proposed. However, these movements are typically provided by different mechanisms within the apparatus, which increases the complexity of not only the physical apparatus but also the control systems required to control the movement. The provision of multiple different mechanisms reduces the mechanical reliability of the apparatus. There also remains a need to make these adjustment mechanisms ever more compact, and in particular to further reduce the hop-on height. Reducing the space requirements of the apparatus also helps to ensure that medical practitioners have unencumbered access to the patient positioned on the support surface.

The present disclosure seeks to address these and other disadvantages encountered in the prior art by providing an improved patient support apparatus.

SUMMARY

An invention is set out in the claims.

FIGURES

Specific implementations are now described, by way of example only, with reference to the drawings, in which:

FIG. 1 depicts an isometric view of an implementation of the radiotherapy device;

FIG. 2 a depicts a top down view of an implantation of the radiotherapy device;

FIG. 2 b depicts a side view of an implantation of the radiotherapy device;

FIG. 2 c depicts an end view of an implantation of the radiotherapy device;

FIG. 3 depicts an isometric view of an implementation of the radiotherapy device comprising wedge assemblies;

FIG. 4 depicts an isometric through view of an implementation of the radiotherapy device comprising wedge assemblies;

FIG. 5 a depicts a side view of an implantation of the radiotherapy device comprising wedge assemblies during tilt of the surface;

FIG. 5 b depicts a side view of an implantation of the radiotherapy device comprising wedge assemblies during tilt of the surface;

FIG. 6 a depicts a top down view of an implantation of the radiotherapy device comprising wedge assemblies during roll of the surface;

FIG. 6 b depicts an end on view of an implantation of the radiotherapy device comprising wedge assemblies during roll of the surface;

FIG. 7 a depicts a side view of an implantation of the radiotherapy device comprising wedge assemblies during tilt of the surface;

FIG. 7 b depicts an end on view of an implantation of the radiotherapy device comprising wedge assemblies during roll of the surface;

FIG. 7 c depicts an end on view of an implantation of the radiotherapy device comprising wedge assemblies during translation of the surface;

FIG. 8 a depicts an isometric through view of an implementation of the radiotherapy device comprising wedge assemblies;

FIG. 8 b depicts a close up isometric through view of an implementation of the radiotherapy device comprising wedge assemblies;

FIG. 9 a depicts a side view of an implantation of the radiotherapy device comprising wedge assemblies during tilt of the surface;

FIG. 9 b depicts a side view of an implantation of the radiotherapy device comprising wedge assemblies during tilt of the surface;

FIG. 9 c depicts an isometric view of an implantation of the radiotherapy device comprising wedge assemblies during tilt of the surface;

FIG. 10 a depicts an end on view of an implantation of the radiotherapy device comprising wedge assemblies during roll of the surface;

FIG. 10 b depicts an isometric view of an implantation of the radiotherapy device comprising wedge assemblies during roll of the surface;

FIG. 11 depicts an isometric view of an implantation of the radiotherapy device comprising wedge assemblies;

FIG. 12 a depicts an isometric view of an implantation of the radiotherapy device comprising a crank and a link;

FIG. 12 b depicts a close up isometric view of an implantation of the radiotherapy device comprising a crank and a link;

FIG. 13 a depicts a side view of an implantation of the radiotherapy device comprising a crank and a link during tilt of the surface;

FIG. 13 b depicts a side view of an implantation of the radiotherapy device comprising a crank and a link during tilt of the surface;

FIG. 14 a depicts an end on view of an implantation of the radiotherapy device comprising a crank and a link during roll of the surface;

FIG. 14 b depicts a side on view of an implantation of the radiotherapy device comprising a crank and a link during roll of the surface;

FIG. 15 a depicts an isometric view of an implantation of the radiotherapy device comprising a pivot member;

FIG. 15 b depicts an end on view of an implantation of the radiotherapy device comprising a pivot member;

FIG. 16 a depicts a side view of an implantation of the radiotherapy device comprising a pivot member during tilt of the surface;

FIG. 16 b depicts a side view of an implantation of the radiotherapy device comprising a pivot member during tilt of the surface;

FIG. 17 a depicts an end on view of an implantation of the radiotherapy device comprising a pivot member during roll of the surface;

FIG. 17 b depicts an end on view of an implantation of the radiotherapy device comprising a pivot member during roll of the surface.

DETAILED DESCRIPTION

By providing a patient support apparatus for a radiotherapy device comprising: a support surface; a base; a first connection assembly connecting the surface and the base, the first connection assembly being connected to the surface at a first connection point, wherein the first connection assembly is coupled to a first driving mechanism configured to effect translation of the first connection point in a substantially vertical direction; a second connection assembly connecting the surface and the base, the second connection assembly being connected to the surface at a second connection point, wherein the second connection assembly is coupled to a second driving mechanism configured to effect translation of the second connection point in the substantially vertical direction; a third connection assembly connecting the surface and the base, the third connection assembly being connected to the surface at a third connection point, wherein the third connection assembly is coupled to a third driving mechanism configured to effect translation of the third connection point in the substantially vertical direction; wherein the third connection assembly further comprises a pivot joint at the third connection point configured to enable relative rotation between the surface and the base; and wherein the first, second and third driving mechanisms are configured to be independently driven to provide rotation and vertical translation of the surface with respect to the base, a number of benefits are provided.

For example, the disclosed patient support surface provides a rigid and precise mechanism that Is easy to control. The patient support surface has enhances simplicity and stability and result in a cost efficient system and compact. The patient support surface can not only provide rotation of the couch but can also translate the surface of the couch, which it does by means of a single compact system. Providing the dual functionality of rotational capability and translation capability enables damage to healthy tissue during treatment to be minimised.

High-Level Overview of a Radiotherapy Device

In accordance with an implementation, FIG. 1 depicts a radiotherapy device suitable for delivering a beam of radiation to a patient during radiotherapy treatment, where the radiotherapy device comprises a patient support apparatus as described herein. The device and its constituent components will be described generally for the purpose of providing useful accompanying information for the present disclosure. The device depicted in FIG. 1 is in accordance with the present disclosure and is suitable for use with the disclosed systems and apparatuses, although not all of the features are necessarily present, or as depicted in FIG. 1 . While the device in FIG. 1 is an MR-linac, the implementations of the present disclosure may be any radiotherapy device, for example a linac device. FIG. 1 shares features common with known devices such as Versa HDTM in particular, the features involved in producing the treatment beam 110.

The device depicted in FIG. 1 is an MR-linac. The device comprises both MR imaging apparatus 112 and radiotherapy (RT) apparatus which may comprise a linac device. In operation, the MR scanner produces MR images of the patient, and the linac device produces and shapes a beam of radiation and directs it toward a target region within a patient's body in accordance with a radiotherapy treatment plan. The usual ‘housing’ which would cover the MR imaging apparatus 112 and RT apparatus in a commercial setting such as a hospital is not depicted in FIG. 1 .

The MR-linac device depicted in FIG. 1 comprises a source of radiation 106. The source of radiation 106 may comprise beam generation equipment, such as one or more of: a source of radiofrequency waves 102, a circulator 118, a source of electrons 105, a waveguide 104, and a target (not shown)The MR-linac may also comprise a collimator 108 such as a multi-leaf collimator configured to collimate and shape the beam, MR imaging apparatus 112, and a patient support apparatus 114. The device also comprises a housing which, together with the ring-shaped gantry defines a bore. The moveable subject support apparatus 114 can be used to move a patient, or other subject, into the bore when an MR scan and/or when radiotherapy is to commence or during treatment. The MR imaging apparatus 112, RT apparatus, and a subject support surface actuator are communicatively coupled to a controller or processor. The controller is also communicatively coupled to a memory device comprising computer-executable instructions which may be executed by the controller.

The RT apparatus comprises a source of radiation 106 and a radiation detector (not shown). Typically, the radiation detector is positioned diametrically opposed to the radiation source 106. The radiation detector is suitable for, and configured to, produce radiation intensity data. In particular, the radiation detector is positioned and configured to detect the intensity of radiation which has passed through the subject. The radiation detector may also be described as radiation detecting means, and may form part of a portal imaging system.

The radiation source 106 defines the point at which the treatment beam 110 is introduced into the bore. The radiation source 106 may comprise a beam generation system, which may comprise a source of RF energy 102, an electron gun 105, and a waveguide 104. The beam generation system is attached to the rotatable gantry 116 so as to rotate with the gantry 116. In this way, the radiation source 106 is rotatable around the patient so that the treatment beam 110 can be applied from different angles around the gantry 116. In a preferred implementation, the gantry 116 is continuously rotatable. In other words, the gantry 116 can be rotated by 360 degrees around the patient, and in fact can continue to be rotated past 360 degrees. The gantry 116 rotates about a mechanical isocenter, which is the point in space about which the gantry 116 rotates and about a fixed axis 119 as shown in FIG. 1 . The radiation isocenter can be defined as the point where the radiation beams intersect. These two isocenters 124 need not be the same, although it may be desirable that they should be. In this disclosure, the term isocenter 124 can refer to either or both of these. The isocenter 124 is located within the radiation plane. The gantry 116 may be ring-shaped. In other words, the gantry 116 may be a ring-gantry with a bore. The gantry 116 may also not be ring-shaped and may instead be an open gantry such as that shown in FIG. 1 .

The source 102 of radiofrequency waves, such as a magnetron, is configured to produce radiofrequency waves. The source 102 of radiofrequency waves is coupled to the waveguide 104 via circulator 118, and is configured to pulse radiofrequency waves into the waveguide 104. Radiofrequency waves may pass from the source 102 of radiofrequency waves through an RF input window and into an RF input connecting pipe or tube. A source of electrons 105, such as an electron gun, is also coupled to the waveguide 104 and is configured to inject electrons into the waveguide 104. In the source of electrons, electrons are thermionically emitted from a cathode filament as the filament is heated. The temperature of the filament controls the number of electrons injected. The injection of electrons into the waveguide 104 is synchronised with the pumping of the radiofrequency waves into the waveguide 104. The design and operation of the radiofrequency wave source 102, electron source and the waveguide 104 is such that the radiofrequency waves accelerate the electrons to very high energies as the electrons propagate through the waveguide 104.

The source of radiation 106 is configured to direct a beam 110 of therapeutic radiation toward a patient positioned on the patient support apparatus 114. The source of radiation 106 may comprise a heavy metal target toward which the high energy electrons exiting the waveguide are directed.

When the electrons strike the target, X-rays are produced in a variety of directions. A primary collimator may block X-rays travelling in certain directions and pass only forward travelling X-rays to produce a treatment beam 110. The X-rays may be filtered and may pass through one or more ion chambers for dose measuring. The beam can be shaped in various ways by beam-shaping apparatus, for example by using a multi-leaf collimator 108, before it passes into the patient as part of radiotherapy treatment.

In some implementations, the source of radiation 106 is configured to emit either an X-ray beam or an electron particle beam. Such implementations allow the device to provide electron beam therapy, i.e. a type of external beam therapy where electrons, rather than X-rays, are directed toward the target region. It is possible to ‘swap’ between a first mode in which X-rays are emitted and a second mode in which electrons are emitted by adjusting the components of the linac. In essence, it is possible to swap between the first and second mode by moving the heavy metal target in or out of the electron beam path and replacing it with a so-called ‘electron window’. The electron window is substantially transparent to electrons and allows electrons to exit the flight tube.

The radiotherapy apparatus/device depicted in FIG. 1 also comprises MR imaging apparatus 112. The MR imaging apparatus 112 is configured to obtain images of a subject positioned, i.e. located, on the subject support apparatus 114. The MR imaging apparatus 112 may also be referred to as the MR imager. The MR imaging apparatus 112 may be a conventional MR imaging apparatus 110 operating in a known manner to obtain MR data, for example MR images. The skilled person will appreciate that such a MR imaging apparatus 112 may comprise a primary magnet, one or more gradient coils, one or more receive coils, and an RF pulse applicator. The operation of the MR imaging apparatus is controlled by the controller.

The controller is a computer, processor, or other processing apparatus. The controller may be formed by several discrete processors; for example, the controller may comprise an MR imaging apparatus processor, which controls the MR imaging apparatus 112; an RT apparatus processor, which controls the operation of the RT apparatus; and a subject support surface processor which controls the operation and actuation of the subject support surface. The controller is communicatively coupled to a memory, i.e. a computer readable medium.

The linac device also comprises several other components and systems as will be understood by the skilled person. For example, in order to ensure the linac does not leak radiation, appropriate shielding is also provided.

The patient support apparatus 114 may serve to support an object. The object may be a human body (such as a patient), an animal body or a material sample. The subject support apparatus 114 is configured to move parallel to the longitudinal axis 113 between a first position substantially outside the bore, and a second position substantially inside the bore. In the first position, a patient or subject can mount the apparatus support surface 114. The subject support apparatus 114, and patient, can then be extended inside the bore, to the second position, in order for the patient to be imaged by the MR imaging apparatus 112 and/or imaged or treated using the RT apparatus. The terms subject and patient are used interchangeably herein such that the subject support apparatus 114 can also be described as a patient support apparatus 114. The subject support apparatus 114 may also be interchangeably referred to in this disclosure as a patient support apparatus 114 or a couch 114.

Adjusting the position of the patient support surface 120 can be desirable during treatment. For example, one approach to minimising a radiation dose received by healthy tissue surrounding a target region is to direct the radiation towards the target region from a plurality of different angles, for example by rotating a source of radiation around the patient by use of a rotating gantry 116. Radiation is emitted in a radiation plane which is co-incident with the plane of the gantry 116 around which the radiation source rotates and radiation may thus be delivered to a radiation isocenter at the centre of the gantry 116 regardless of the angle to which the radiation head is rotated around the gantry 116. Because the radiation is applied from a plurality of different angles, the same, high, cumulative radiation dose is not built up in the healthy tissue since the specific healthy tissue the radiation passes through varies with angle. Therefore, a unit volume of the healthy tissue receives a reduced radiation dose relative to a unit volume of the target region. In this case, it is desirable to be able to position the target region at the isocenter to ensure that the maximum radiation dose is delivered to the target region and the minimum dose is received by healthy tissue. It is therefore important to be able to accurately position the support surface 120 so that the target region is at the desired location, which may be the isocenter. This can be achieved by translating the support surface 120 using the patient support apparatus 114 described herein.

Treatments that utilise rotation of the gantry 116 in this manner are known as coplanar. However, after the radiation source has been rotated 180°, it will be appreciated that any subsequent radiation beams begin to pass through regions of healthy tissue which have already been irradiated. This increases the radiation dose applied to healthy tissue. Accordingly, when using such a method the volume of healthy tissue available to spread the radiation dose is relatively small, thus imposing restrictions on the treatment which can be provided by such devices.

Therefore, an alternative approach to minimising the radiation dose received by healthy tissue surrounding a target region is to rotate the patient relative to the plane of radiation. For example, by pitching or rolling the support surface 120 on which the patient lies. As the angle of the support surface 120 (and therefore patient) varies relative to the plane of the gantry 116, the healthy tissue the radiation passes through varies accordingly. In order to further reduce the radiation dose relative to a unit volume of the target region, it is desirable to provide a treatment that combines the rotation of both the radiation source and the support surface 120. However, when rotating the support surface 120, this may also cause a translation of the target region. For example, when pitching the support surface 120 forward, if the target region is not located at the axis of rotation (which may not always be possible), the target region will translate in a vertical direction if it is not compensated for using other means. The translation of the target region will be proportional to its distance from the axis of rotation of the support surface 120 and the amount of rotation.

High-Level Overview of a Patient Support Apparatus According to the Present Disclosure

Reference is made to FIGS. 2 a-c . FIGS. 2 a-c are simplified schematics of a patient support apparatus 214 according to the present disclosure. FIG. 2 a shows the positions of first, second and third connection points 230, 232 and 234 with respect to subject support surface 220. FIG. 2 b depicts the subject support surface from the side. FIG. 2 c depicts the subject support surface from the back. The patient support surface apparatus 214 may be used with the radiotherapy device 100 depicted in FIG. 1 .

The patient support apparatus 214 comprises a support surface 220. The patient support apparatus 214 not only enables rotation of the support surface 220 but also enables translation of the support surface 220. The translation of the support surface 220 may be done in order to compensate for the movement caused by rotation of the support surface 220. However, the translation of the support surface 220 may also be independent of any rotation of the support surface 220. By providing the dual functionality of rotational capability and translation capability, damage to healthy tissue can be minimised during treatment of a patient.

It is also desirable to keep the apparatus as compact and as reliable as possible. Keeping the apparatus compact ensures that patients can easily be positioned and also that medical practitioners will have unencumbered access to the patient. Known systems do not provide the dual functionality of rotational capability and translation capability and do not do so with a single compact system in the manner provided by the patient support apparatus 214 and its specific implementations disclosed herein.

The subject support apparatus 214 comprises a support surface 220 on which a patient can lie. The subject support apparatus 214 also comprises a base 222 that supports the support surface 220 by means of first, second and third connection assemblies 224, 226, 228 connected to the surface at first, second and third connection points 230, 232, 234. The first, second and third connection assemblies 224, 226, 228 are also coupled respectively to first, second and third driving mechanisms (not shown). Each of the driving mechanisms is operable to effect translation of the respective connection points 230, 232, 234 in a substantially vertical direction. The third connection point 234 consists of a pivot joint connecting the third connection assembly 228 to the support surface 220. By driving each of the driving mechanisms 225, 227, 229, either independently or together, the support surface 220 can be made to pitch and roll, as well as translate vertically and longitudinally. Each of the driving mechanisms 225, 227, 229 can be controlled independently or in conjunction with each other by means of one or more processors. The processor may be comprised within the patient support apparatus 214 or may be located separately, for example, the processor(s) may be located within a control room. The processor is configured to control the first, second and third driving mechanisms to provide rotation and/or vertical translation of the surface 220 as part of a treatment plan.

In order to effect translation, one or more of the driving mechanisms 225, 227, 229 may comprise a linear actuator. For example, the third driving mechanism 229 may comprise a linear actuator configured to raise or lower the third connection point 234 to cause the support surface 220 or a portion thereof to translate in a vertical, or substantially vertical, direction. The vertical direction is the direction that is perpendicular to both the longitudinal axis and the lateral axis of the base 222. That is, the axis that is perpendicular to the face of the surface 220 when it is in its neutral position.

For example, the base 222 is a planar surface, and the substantially vertical direction is perpendicular to a plane of the planar surface. In another example, the third driving mechanism 229 comprises a ball screw that translates rotational motion of a motor into linear motion of the third connection point 234 in the vertical direction.

The third connection point 234 is a pivot joint that acts as a pivot point. When the support surface 220 is pitched and/or rolled, the axis of rotation of the pitch and/or roll passes through the third connection point 234. The third connection point 234 defines a center of rotation of the surface 220. The pivot point therefore allows free spherical rotation. In one example, the pivot point comprises one of a universal joint and a spherical bearing, but it is not limited to these examples and any other connection that allows free spherical rotation would also work.

Each of the connection points 230, 232, 234 is located on the underside of the support surface 220 so that the top of the support surface 220 remains uninhibited, thereby allowing a patient to lie on the surface 220. The third connection point 234 is located along a longitudinal centreline of the surface 220. This helps to make the roll of the support surface symmetric regardless of the direction of roll.

In one example, as shown in, for example, FIGS. 2-6 b, the first and second connection points 230, 232 are equally spaced on opposite sides of a longitudinal centreline of the surface 220 and are equally distanced from a transverse centreline of the surface 220 at a position towards a first end of the surface 220, and the third connection point 234 is located at a position towards a second end of the surface 220. In this example the first and second ends are on the opposite sides of the transverse centreline of the surface 220.

In another example, as shown in, for example, FIGS. 8 a -11, the first connection point 230 is located along a longitudinal centreline of the surface 220, whilst the second connection point 232 is located at a position that is spaced apart from the longitudinal centreline of the surface 220. In other words, the first and second connection points 230, 232 are asymmetric about the longitudinal centreline of the surface 220.

Specific Implementations

Specific implementations of the patient support surface described above in relation to FIGS. 2 a-c will now be described. The skilled person will appreciate that features of these different implementations and examples may be regarded as interchangeable. For example, features from the first disclosed example may be used within the arrangement of the second disclosed example.

First General Example: FIGS. 3-11.

One implementation is shown from different perspectives and in different positions in FIGS. 3-11 . These figures show that the first and second connection points 330, 332 are connected to first and second connection assemblies 324, 326. Each of the first and second connection assemblies 324, 326 comprises or is itself a wedge assembly. The first and second connection points 330, 332 connected to the support surface 320, climb on wedges 336, 338 to convert a substantially horizontal translation provided to the wedges 336, 338 by one of the first and second drive mechanisms 336, 338 to a substantially vertical translation. By moving the wedges 336, 338 in the same direction, the surface 320 pitches about a pivot point. If wedges 336, 338 move synchronously in opposite directions, the surface 320 rolls.

As shown in FIG. 3 , each of the first and second connection assemblies 324, 326, which are themselves wedge assemblies, comprises a wedge 336, 338 that is configured to move linearly. Each wedge 336, 338 is configured to be moved by a respective driving mechanism 325, 327. This can be done by any appropriate means but in this example the driving mechanisms 325, 327 are directly connected to the wedges 336, 338 respectively by means of a lateral protrusion from the wedges 336, 338. The driving mechanisms 325, 327 may for example, be a linear actuator such as, but not limited to: a mechanical actuator that converts rotary motion into linear motion by means of a screw, a wheel and axle or a cam; a hydraulic actuator; or a pneumatic actuator. In this example, the driving mechanisms 325, 327 are actuators that make use of a motor and ball screw. The driving mechanisms 325, 327 are connected to the base 322, which itself fixed, for example, to the floor. In this way, the driving mechanisms 325, 327 are configured to move one of the wedges with respect to the base 322 to thereby effect movement of a slider 342 with respect to the wedge.

In this example, each wedge 336, 338 is broadly triangular in shape, with the connection points 330, 332 on the hypotenuse. Each of the connection points 330, 332, 334 consists of a spherical contact bearing 340 that permits angular rotation about a central point of the bearing in two orthogonal directions. The surface 320 comprises a number of attachment shafts on its underside and the spherical contact bearings 340 are connected to these attachment shafts. In this example, a first attachment shaft is axially fixed to a spherical contact bearing 340 at the first connection point 330. A second attachment shaft is able to slide axially in relation to the spherical contact bearing 340 located at the second connection point 332. A third attachment shaft is axially fixed to a spherical contact bearing 340 at the third connection point 334. In the example shown in FIG. 4 , the spherical contact bearings 340 located at the first and second connection points 330, 332 are attached to a linear guide, also referred to as a slider 342 that is configured to move along the hypotenuse of the respective wedge 336, 338. The wedges 336, 338 may comprise a guide rail onto which the respective slider 342 may be movably attached. As a wedge 336, 338 is translated in a linear direction, the slider 342 rises up (or down) the wedge 336, 338 thereby effecting translation of the connection point 330, 332 associated with that wedge 336, 338.

The spherical contact bearing 340 at the third connection point 334 is coupled to a third driving mechanism 329 configured to effect translation of the third connection point 334 in the substantially vertical direction. In this example the third driving mechanism 329 is an actuator that make use of a motor and ball screw. In one example, the third driving mechanism 329 effects vertical motion by a direct connection to the spherical contact bearing 340 at the third connection point 334. In another example, the third driving mechanism 329 also connects to a third wedge assembly and effects vertical translation at the third connection point 334 by converting a substantially horizontal translation to a substantially vertical translation through use of a wedge assembly. In one example, the third wedge assembly is placed at an angle to the first and second wedge assemblies 336, 338. For example, the slope of the third wedge assembly may be in an opposite direction to the slope of the first and second wedge assemblies 336, 338.

As shown in FIG. 4 , the connection assemblies 324, 326, 328 and drive mechanisms 325, 327, 329 may be set completely or partially into the base 322 of the patient support apparatus 314. This helps to keep the patient support apparatus 314 compact.

The basic principle is that two support points, connected to the support surface, climb on wedges 336, 338. By moving the wedges 336, 338 in the same direction, the surface 320 pitches about a pivot point. If wedges 336, 338 move synchronously in opposite directions, the surface 320 rolls.

FIGS. 5 a and 5 b illustrate how the patient support apparatus 314 can be used to pitch the support surface 320. In FIG. 4 a , the first and second wedge assemblies 324, 326 are in a first position located towards the front of the patient support apparatus 314. Throughout this disclosure, for consistency, the front of the patient support apparatus 314 will refer to the end at which the third connection assembly 328 is located. When the first and second wedge assemblies 324, 326 are in the first position towards the front of the patient support apparatus 314, the sliders 342 are position towards the bottom of each wedge (the bottom refers to the direction close to the base 322). During operation, the first and second driving mechanisms 325, 327 effect translation of the wedge assemblies 324, 326 towards the rear (the end opposite the front) of the patient support apparatus 314. In this example, the wedge assemblies 324, 326 are translated rearwards by an equal distance, so that they arrive at a second position as shown in FIG. 5 b . As can be seen in FIG. 5 b , as the wedge assemblies 324, 326 are translated rearwards, the sliders 342 on top of each of the wedge assemblies 324, 326 are caused to rise up the wedge assemblies 324, 326. This occurs because, in this example, the third connection assembly 328 does not translate along the plane of the base 322. Therefore, as the sliders 342 rise up the wedge assemblies 324, 326, the first and second connection points 330, 332 are translated in a substantially vertical direction. This causes the support surface 320 to pitch forwards. As shown in FIG. 5 b , this pitch is about an axis of rotation that passes through the third connection point 334.

The patient support apparatus 314 can be configured such that, when the support surface 320 is level, the sliders 342 on which it is supported are approximately half way up each of the wedges. In this example, by moving the first and second wedge assemblies 324, 326 rearward from this position the surface 320 will be pitched forwards. In this example, by moving the wedge assemblies 324, 326 forwards from this position the surface 320 will be pitched backwards.

FIGS. 6 a and 6 b illustrate how the patient support apparatus 314 can be used to roll the support surface 320. In a position of equilibrium, the patient support apparatus 314 is configured such that the first and second wedge assemblies 324, 326 and their respective sliders 342 are parallel with one another, resulting in a support surface 320 the plane of which is parallel to the base 322. From this position, as shown in FIG. 6 a , the first and second wedge assemblies 324, 326 can be translated in opposite directions to one another. For example, the first driving mechanisms 325 translates the first wedge assembly 324 forwards and the second driving mechanism 327 translates the second wedge assembly 326 backwards. This causes the slider 342 of the first wedge assembly 324 to move down the wedge of the first wedge assembly 324. This causes the slider 342 of the second wedge assembly 326 to move up the wedge of the second wedge assembly 326. Therefore, the first connection point 330 is translated downwards and the second connection point 332 is translated upwards. In one example, the first and second driving mechanisms 325, 327 move the first and second wedge assemblies 324, 326 an equal distance but in opposite directions. The third connection point 334 which is located along the longitudinal centreline of the support surface 320 therefore acts as a pivot point. The support surface 320 therefore rolls anti clockwise in the direction of the first connection assembly 330.

FIG. 6 b is an end on view of the patient support apparatus 314 and illustrates how the surface 320 rolls towards the second connection assembly 326 when the first and second wedge assemblies 324, 326 are translated in opposite directions to one another. In the example shown in FIG. 6 b , the first and second wedge assemblies 324, 326 are translated in the opposite directions to those described above in relation to FIG. 6 a.

FIGS. 7 a and 7 b further illustrate how a patient lying on the support surface 320 may be pitched or rolled respectively. As shown in FIG. 7 c , it is also possible to use the patient support apparatus 314 to vertically translate the support surface 320. For example, by retracting the first and second wedge assemblies 324, 326 as shown in FIG. 5 b , whilst also operating the third driving mechanism 329 to translate the third connection point 334 upwards in a vertical or substantially vertical direction, the support surface 320 may be translated vertically upwards as a whole. For example, the translation of the third connection point 334 may be controlled to match the translation of the first and second connection points 330, 332 so that the support surface 320 does not pitch at all but is instead raised vertically without any rotation. In another example, the pitch of the support surface 320 by the first and second connection assemblies 324, 326 may result in a target region moving away from the isocenter because the target region may not be located along the axis of rotation. In order to reposition the target region at the isocenter, the third driving mechanism 329 can be operated in conjunction with the first and second driving mechanisms 325, 327 so that the desired amount of pitch is achieved whilst also maintaining a target region at the desired location. By operating the third driving mechanism 329 to move the front pivot point (the third connection point 334), the point of rotation can be adjusted. It will be appreciated that a similar combination of combined operation of the first, second and third driving mechanisms 325, 327, 329 or any combination thereof may be utilised to achieve optimal rotation and positioning of the support surface 320 when rolling the support surface too and regardless of the direction of pitch and/or roll.

The operation of the first, second and third driving mechanisms 325, 327, 329 is controlled by one or more controllers operated by one or more processors that is configured to calculate the required translation of the first, second and third connection assemblies 324, 326, 328 in order to achieve a desired rotation and position of the support surface 320 and/or a patient or target region that is on top of the support surface 320. This control may form part of a treatment plan. The driving mechanisms 325, 327, 329 can move synchronous or independently of each other. For example, it is possible to cause both a roll of 3 degree and a pitch of 0.6 degrees by actuating only one of the driving mechanisms 325, 327 whilst the other driving mechanism is fixed. Since one connection point 330, 332 can slide on its axis and the non-sliding connection point 330, 332 is offset from the centreline, this also creates a slight rotation about the vertical/Z-axis. For example, the surface 320 may rotates about 0.09 degrees. However, if the non-sliding connection point 330, 332 were located along the longitudinal centreline of the support surface 320, this rotation will not occur.

FIGS. 3-7 c show a patient support apparatus 314 that has the first and second connection points 330, 332 equally spaced on opposite sides of a longitudinal centreline of the surface 320. The examples shown in FIGS. 8 a -11 have a first connection point 330 that is located along a longitudinal centreline of the surface 320 and a second connection point 332 that is located at a position that is spaced apart from the longitudinal centreline of the surface 320. The principles of operation described above in relation to the example shown in FIGS. 3-7 c also apply to the examples shown in FIGS. 8 a -11. In both examples, the support surface 320 is resting on three points with joints free to rotate in any direction. The support points are connected to a mechanism that pushes the joints vertically. Rotational movement is created by linear motion.

In the examples shown in FIGS. 8 a -11, the first and second driving mechanisms 325, 327 are situated in between the first and second connection points 330, 332 and the third connection point 334. In the examples shown in FIGS. 3-7 c, the first and second driving mechanisms 325, 327 are situated on the opposite side of the first and second connection points 330, 332 to the third connection point 334. As illustrated in, for example, FIG. 8 b , the wedges 336, 338 are supported along one or more linear guide rails 344. The linear guide rails 344 are themselves fixed to the base 322. The linear guide rails 344 are parallel to the base 322. The linear guide rails 344 may be fixed to the base 322 via an intermediary block 346. The linear guide rails 344 enable the wedges 336, 338 to slide along them when driven by their respective driving mechanisms 325, 327.

In some examples, the driving mechanisms 325, 327, 329 are equally sized and/or powered. In the example shown in FIG. 8 b , the first driving mechanism 336 is a first actuator and the second driving mechanism 338 is a second actuator and the first actuator is smaller and less powerful than the second actuator. In this example the second actuator is situated along a longitudinal centreline of the surface 320 whilst the first actuator is located at a position that is spaced apart from the longitudinal centreline of the surface 320. In one example of producing pitch, as shown in FIGS. 9 a-9 c , the second actuator moves (the second, in this case larger, driving mechanism 327) whilst the first actuator (the first, in this case smaller, driving mechanism 325) stays fixed. This causes the support surface 320 to pitch. In one example of producing roll, as shown in FIGS. 10 a and 10 b , the first actuator moves (the first, in this case smaller, driving mechanism 325) whilst the second actuator (the second, in this case larger, driving mechanism 327) stays fixed. This causes the support surface 320 to roll.

As shown in FIG. 11 , the third driving mechanism 329 is connected to a third wedge assembly. The third wedge assembly is placed at an angle to the first and second wedge assemblies 336, 338. The slope of the third wedge assembly may be in an opposite direction to the slope of the first and second wedge assemblies 336, 338. The third wedge assembly effects vertical translation of the third connection point 334 by converting a substantially horizontal translation provided by the third driving mechanism 329 to a substantially vertical translation. As described above, the third driving mechanism 329 can be operated in conjunction with the first and second driving mechanisms 325, 327 as a way to fine tune the height of the surface 320 after pitching or rolling. For example, the third driving mechanism 329 may be controlled to effect a vertical translation of the surface 320 after pitch and/or rolling the surface 320 such that a target region is maintained at an isocenter of the radiotherapy device.

The components of the patient support apparatus 314 may be made from any appropriate materials. For example, the support surface 320 may be made from a metal, for example steel, aluminium, or a composite materials. For example, the support surface 320 may be made from carbon fibre which is lightweight and stiff, thereby increasing the rigidity of the support surface 320 (and so minimising any deflection) whilst also reducing the weight of the support surface 320 which reduces the demands on the driving mechanisms 325, 327, 329. The base 322 may also be made from a metal, for example steel, or any other appropriate material. The components of the wedge assemblies may also be made from a metal, for example steel, or any other appropriate material. In one example, the wedge has an angle of 30 degrees with a slider running on a linear guide.

Whilst the wedges 336, 338 shown in FIGS. 3-11 have a slope that rises in the direction of the third connection point 334, it will be appreciated that the patient support system 314 may instead use wedges 336, 338 that have a slope rising in the opposite direction. This would reverse the direction of movement caused by movement of the wedges 336, 338 and would be taken into account by the processor when controlling the driving first, second and third mechanisms 325, 327, 329.

Second General Example: FIGS. 12 a -14 b.

One implementation is shown from different perspectives and in different positions in FIGS. 12 a-14 b . These figures show an alternative configuration of the first and second driving mechanisms 425, 427 and the first and second connection assemblies 424, 426. Each of the first and second connection assemblies 424, 426 comprises a crank 450 that is configured to be rotated about a fixed axis. The crank 450 is connected to the surface 420 at the first/second connection point 430, 432 either directly or via one or more other components. For example, the crank 450 is coupled to the surface 420 by a link 452. The link 452 is coupled to the crank 450 at a position on the crank 450 located radially outwards from the fixed axis of rotation. The first and second driving mechanisms 425, 427 are configured to cause rotation of the crank 450 about the fixed axis. The rotation of the crank 450 by the first/second driving mechanism 425, 427 effects translation of the respective link and connection point 430, 432 in a substantially vertical direction.

As shown in FIGS. 12 a and 12 b , each of the first and second connection assemblies 424, 426 comprises a crank 450 that is coupled to the first/second driving mechanisms 425, 427. Each of the first and second driving mechanisms 425, 427 comprises a belt 454 and a motor 456 configured to drive the belt 454, wherein the crank 450 is configured to be rotated by a movement of the belt 454. In the example shown in FIGS. 12 a and 12 b , each of the first and second driving mechanisms 425, 427 comprises a drive wheel 458 that is configured to be rotated by a movement of the belt 454. In one example, the drive wheel 458 is notched and engages with corresponding notches on the belt 454. In another example, a high friction material is used for the belt 454 to increase engagement with the drive wheel 458. The drive wheel 458 is attached to the crank 450 such that rotation of the drive wheel 458 causes rotation of the crank 450. In one example, the drive wheel 458 is connected to the crank 450 by a drive shaft 460. In another example, there is no drive shaft 460 and the drive wheel 458 is attached to the crank 450 by other means, for example, directly by mechanical fixation. In one example, the drive shaft 460 connects the drive wheels 458 of the first and second drive mechanisms 425, 427. The drive shaft 460 is rotatably supported by the base 422 of the patient support apparatus 414.

Each of the first and second connection assemblies 424, 426 shown in FIGS. 12 a and 12 b also comprise a link 452 coupling the crank 450 to the support surface 420. In one example, the links 452 of the first and second connection assemblies 424, 426 are connected by a shaft 462. In one example, the crank 450 is connected to the associated link 452 by the shaft 462. For example, the link 452 may comprise a spherical bearing 464 through which the shaft 462 passes. The spherical bearing(s) 464 prevents the shaft 462 from translating more than a predetermined distance, whilst allowing the shaft 462 to rotate relative to the crank(s) 450. In one example, each of the first and second connection assemblies 424, 426 comprises first and second spring packages 468, 466, wherein the first spring package 468 is situated in between and biased against an outside of the crank 450 and an inside of the link 452, and the second spring package 466 is situated on an outside of the link 452 and is biased against the outside of the link 452. In one example, the crank 450 is also connected to the shaft 462 by means of a spherical bearing 470. The shaft 462 is parallel to the transverse axis of the surface 420.

The link 452 is coupled to the support surface 420 either directly or indirectly. In the example shown in FIGS. 12 a and 12 b , each link 452 is movably coupled to the support surface at the first/second connection point 430, 432 by a linearly movable slider 472. In one example, the linearly movable slider 472 is fixedly connected to the corresponding link 452 and movably connected to the surface 420. In another example, the linearly movable slider 472 is fixedly connected to the surface 420 and movably connected to the corresponding link 452. For example, the link 452 is fixedly connected to a guide rail 474, wherein the linearly movable slider 472 is movably connected to the guide rail 474 but fixedly connected to the surface 420. Many configurations that allow relative movement between the link 452 and the surface 420 are envisaged and would also be suitable for use in the patient support apparatus 414 disclose herein.

The third connection point 434, as described previously in relation to the previous implementations, consists of a pivot joint connecting the third connection assembly 428 to the support surface 420. For example, the third connection point 434 consists of a spherical contact bearing 440 that permits angular rotation about a central point of the bearing in two orthogonal directions.

The third driving mechanism 429, as described previously in relation to the previous implementations, may comprise a linear actuator configured to raise or lower the third connection point 434 to cause the support surface 420 or a portion thereof to translate in a vertical, or substantially vertical, direction. The vertical direction is the direction that is perpendicular to the longitudinal axis of the base 422. In another example, the third driving mechanism 429 comprises a ball screw that translates rotational motion of a motor into linear motion of the third connection point 434 in the vertical direction.

The patient support apparatus 414 also comprises a processor configured to control rotation of the cranks 450 of the first and second connection assemblies 424, 426 by operation of the first and second driving mechanisms 425, 427. As shown in FIGS. 13 a and 13 b , by rotating the crank 450 of the first connection assembly 424 and the crank 450 of the second connection assembly 426 synchronously, the patient support apparatus can 414 cause the surface 420 to pitch. In one example, the first and second connection assemblies 424, 426 are configured such that, as the first and second driving mechanisms 425, 427 cause the respective belts 454 to turn, the cranks 450 are rotated upwards and towards the driving mechanisms 425, 427. This causes the respective connection points 430, 432 to translate in a substantially vertical direction.

As shown in FIGS. 14 a and 14 b , the first and second driving mechanisms 425, 427 can also be controlled to rotate the crank 450 of the first connection assembly 424 and the crank 450 of the second connection assembly 426 asynchronously to cause the surface 420 to roll. For example, the first driving mechanism 425 may cause rotation of the crank 450 of the first connection assembly 424 and so effect translation of the first connection point 430 upwards in a substantially vertical direction, whilst not operating the second driving mechanism 427. Thus, the second connection point 432 is not translated whilst the first connection point 430 is translated vertically, thereby causing the surface 420 to roll towards the second connection point 432. Alternatively, the second driving mechanism 427 may also be operated but may cause a differing amount of rotation of the respective crank 450, thereby also causing the surface 420 to roll. For example, the rotation of the second crank 450 may be in a different direction from the rotation of the first crank 450.

As described in relation to the previous implementation, it is also possible to operate the third driving mechanism 429 to effect translation of the surface 420 as a whole either with or without rotation.

The driving mechanisms 425, 427 may comprise an electric motor, for example brushless DC motor. The components of the patient support apparatus 414 may be made of any appropriate materials. For example, the crank 450, the link 452, the drive shaft 460, the shaft 452, the drive wheel 458, the linearly movable slider 472 and the guide rail 474 may be made of any of a metal such as steel, titanium, aluminium or an alloy, a composite material such as carbon fibre, or other suitable material.

Where components are fixedly connected, they may be connected using any appropriate means. For example, they may be screwed, bolted, welded and/or glued together.

This implementation provides a compact, simple and reliable means for manoeuvring the surface 420 of the patient support apparatus 414. By providing the dual functionality of rotational capability and translation capability, damage to healthy tissue can be minimised during treatment of a patient.

Third General Example: FIGS. 15 a-17 b

One implementation is shown from different perspectives and in different positions in FIGS. 15 a-17 b . These figures show that each of the first and second connection assemblies 524, 526 comprises a pivot member 580 connecting the driving mechanisms 525, 527 and the surface 520 that is configured to effect vertical translation of the first and second connection points 530, 532. The pivot member 580 is connected to the base 522 in a lever arrangement, wherein a first end 582 of the pivot member 580 is coupled to the first or second driving mechanism 525, 527 and a second end 584 of the pivot member 580 is connected (either directly or indirectly) to the support surface 520. The first and second driving mechanisms 525, 527 are configured to actuate the first end 582 of the pivot member 580, which causes the pivot member 580 to pivot about an axis of rotation that is defined by the connection 586 of the pivot member to the base 522. The pivoting of the pivot member 580 causes rotation and/or vertical translation of the surface 520 with respect to the base 522. In one example, the pivot axis of rotation of the pivot member 580 is at a location on the pivot member 580 between the connection of the pivot member 580 to the driving mechanism 525, 527 and the connection of the pivot member 580 to the support surface 520.

Each of the first and second connection assemblies 524, 526 is movably connected to the support surface 520. In one example, sliders 588 connect the pivot members 580 of the first and second connection assemblies 524, 526 to the underside of the support surface 520. In one example, each of the first and second connection assemblies 524, 526 further comprises a linear guide block 590 connected to the second end 584 of the pivot member 580, wherein the linear guide block 590 is movably coupled to the slider 588. In another example, the linear guide block 590 may be fixedly connected to the underside of the support surface 520 and the slider 588 is movably connected to the pivot member 580. Other arrangements that allow relative motion between the pivot member 580 and the surface 520 are also possible.

In one example, the linear guide block 590 is configured to move linearly along a longitudinal axis of the slider 588. In one example, the slider 588 is configured to move linearly along a longitudinal axis of the linear guide block 590. This allows the surface 520 to move longitudinally with respect to the pivot member 580 and the base 522 to which the pivot member 580 is connected. The linear guide block 590 and the slider 588 and configured to rotate relative to each other. In one example, the linear guide block 590 is free in rotation about the slider 588 and the axis of rotation of the linear guide block 590 is a longitudinal axis of the slider 588. Where the slider 588 is fixedly connected to the surface 520, this means that the surface is free in rotation relative to the linear guide block 590, the pivot member 580 and the base 522.

In one example, each of the first and second driving mechanisms 525, 527 comprises an actuator connected at a first end to the base 522 and at a second end to the pivot member 580. As shown in FIG. 15 b , the patient support apparatus 514 is configured to be arranged in a neutral position, in which the surface 520 is substantially horizontal (the plane of the surface 520 is parallel with the plane of the top of the base 522 and/or the floor). From the neutral position, the first and second driving mechanisms 525, 527 can be operated to pitch the surface 520 either forwards or backwards as shown in FIGS. 16 a and 16 b . In one example, the first and second driving mechanisms 525, 527 are actuators that are operated synchronously. By retracting the actuators, the pivot members 580 are rotated such that the first and second connection points 530, 532 are lowered, thereby pitching the surface 520 up as shown in FIG. 16 a . As the pivot members are rotated, the slider 588 is configured to move relative to the linear guide block 590, thereby accommodating for any longitudinal change of location of the first and/or second connection point 530, 532. By extending the actuators, the pivot members 580 are rotated such that the first and second connection points 530, 532 are raised, thereby pitching the surface 520 down as shown in FIG. 16 b.

During the operation shown in FIGS. 16 a and 16 b , the third connection point 534 acts as a pivot point about which the surface 520 rotates. In one example, the third connection point 534 is held stationary. In another example, the third driving mechanism 529 may effect translation of the third connection point 534 to accentuate the rotation of the surface 520. For example, if the first and second connection points 530, 532 are lowered such that the surface 520 pitches up, the third driving mechanism 529 may also be controlled to raise the third connection point 534 so as to increase the amount that the surface 520 is pitched up. In another example, the third driving mechanism 529 may instead be controlled to raise/lower the third connection point 534 by the same amount as the first and second connection points 532 so that the surface 520 is translated vertically without rotation.

As shown in FIGS. 17 a and 17 b , the connection assemblies 524, 526, 528 can also be used in conjunction with the driving mechanisms 525, 527, 529 to cause the surface 520 to roll. For example, the actuator if the first driving mechanism 525 may be extended, thereby raising the first connection point 530, whilst the second driving mechanism 527 is retracted, thereby lowering the second connection point 532. This causes the surface 520 to roll towards the second connection point 532 as shown in FIG. 17 a . If the operation of the driving mechanisms 525, 527 were reversed, the surface 520 would roll in the other direction, towards the first connection point 530. As shown in FIGS. 17 a and 56 b , as the surface rolls, the sliders 580, which are fixedly attached to the surface 520, rotate with respect to the linear guide blocks 588. This enables the surface 520 to roll unencumbered by the attachment to the connection assemblies 524, 526. In one example, the third connection point 534 is held stationary. In another example, the third driving mechanism 529 may effect translation of the third connection point 534 to accentuate the rotation of the surface 520.

By providing the dual functionality of rotational capability and translation capability, damage to healthy tissue can be minimised during treatment of a patient. By providing a patient support apparatus 214, 314, 414, 515 as described above, the support surface 220, 320, 420, 520 can be reliably adjusted. The patient support apparatus 214, 314, 414, 515 is also kept very compact due to the relatively simple mechanism utilised to move the support surface 220, 320, 420, 520 and by, for example, recessing the drive mechanisms 325, 425, 525, 327,427, 527, 329, 429, 529 and/or the connection assemblies 324, 424, 524, 326, 426, 526, 328, 428, 528 in the base 322. Keeping the apparatus compact ensures that patients can easily be positioned and also that medical practitioners will have unencumbered access to the patient.

The above implementations have been described by way of example only, and the described implementations and arrangements are to be considered in all respects only as illustrative and not restrictive. It will be appreciated that variations of the described implementations and arrangements may be made without departing from the scope of the invention. 

1. A patient support apparatus for a radiotherapy device comprising: a support surface; a base; a first connection assembly connecting the support surface and the base, the first connection assembly being connected to the support surface at a first connection point, wherein the first connection assembly is coupled to a first driving mechanism configured to effect, translation of the first connection point in a substantially vertical direction; a second connection assembly connecting the support surface and the base, the second connection assembly being connected to the support surface at a second connection point, wherein the second connection assembly is coupled to a second driving mechanism configured to effect translation of the second connection point in the substantially vertical direction; and a third connection assembly connecting the support surface and the base, the third connection assembly being connected to the support surface at a third connection point, wherein the third connection assembly is coupled to a third driving mechanism configured to effect translation of the third connection point in the substantially vertical direction; wherein the third connection assembly further comprises a pivot joint at the third. connection point configured to enable relative rotation between the support surface and the base, and wherein the first, second and third driving mechanisms are configured to be independently driven to provide rotation and vertical translation of the support surface with respect to the base. 2-4. (canceled)
 5. The patient support apparatus of claim 1, further comprising: a processor configured to control the first, second, and third driving mechanisms to provide at least one of rotation or vertical translation of the support surface as part of a treatment plan.
 6. The patient support apparatus of claim 1, wherein at least one of each of the first, second, and third connection points is a fixed position on an underside of the support surface or wherein the pivot joint comprises one of a universal joint or a spherical bearing.
 7. (canceled)
 8. The patient support apparatus of claim 1, wherein the third connection point is located along a longitudinal centerline of the support surface. 9-10. (canceled)
 11. The patient support apparatus of claim 1, wherein the first connection point and second connection point are equally spaced on opposite sides of a longitudinal centerline of the support surface and are equally distanced from a transverse centerline of the support surface at a position substantially near a first end of the support surface, wherein the third connection point is located at a position substantially near a second end of the support surface, wherein the first connection point is located along a longitudinal centerline of the support surface, and wherein the second connection point is located at a position spaced apart from the longitudinal centerline of the support surface.
 12. (canceled)
 13. The patient support apparatus of claim 1, wherein each of the first connection assembl and the second connection assembly is a wedge assembly configured to convert a substantially horizontal translation provided by one of the first and second drive mechanisms to a substantially vertical translation.
 14. The patient support apparatus of claim 13, wherein each wedge assembly includes: a wedge supported by the base; and a slider movably connected to and supported by the wedge and connected to the support surface at one of the first and second connection points, wherein movement of the slider with respect to the wedge effects translation of at least one of the first connection point or the second connection point in the substantially vertical direction.
 15. The patient support apparatus of claim 14, wherein each wedge is a translatable wedge, and each of the first drive mechanism and the second drive mechanism is configured to move a particular wedge with respect to the base to thereby effect movement of the slider with respect to the particular wedge.
 16. The patient support apparatus of claim 14, wherein the third driving mechanism comprises a third wedge assembly, and wherein each wedge assembly further comprises: a spherical contact bearing which connects the slider to the support surface.
 17. (canceled)
 18. The patient support apparatus of claim 1, wherein each of the first connection assembly and the second connection assembly comprises: a crank configured to be rotated about a fixed axis of rotation by at least one of the first driving mechanism or the second driving mechanism; and a link coupled to the support surface and to the crank at a position on the crank located radially outwards from the fixed axis of rotation.
 19. The patient support apparatus of claim 18, wherein each of the first connection assembly and the second connection assembly includes a shaft, wherein the crank of the first connection assembly is connected to the crank of the second connection assembly by the shaft, and wherein each link is coupled to each crank by the shaft.
 20. (canceled)
 21. The patient support apparatus of claim 19, wherein each of the cranks is connected to the shaft by a first spherical bearing and each of the links is coupled to the shaft by a second spherical bearing.
 22. The patient support apparatus of claim 18, wherein the link is movably coupled to the support surface at, at least one of the first connection point or second connection point respectively by a linearly movable slider.
 23. The patient support apparatus of claim 22, wherein the linearly movable slider is fixedly connected to either the link or the support surface.
 24. (canceled)
 25. The patient support apparatus of claim 19, further comprising a processor wherein the processor is configured to: rotate the crank of the first connection assembly and the crank of the second connection assembly synchronously to cause the support surface to pitch; and. rotate the crank of the first connection assembly and the crank of the second connection assembly asynchronously to cause the support surface to roll.
 26. The patient support apparatus of claim 19, wherein each of the first driving mechanism and the second driving mechanism includes: a belt; and a motor configured to drive the belt, wherein e crank is configured to be rotated by a movement of the belt.
 27. The patient support apparatus of claim 1, wherein each of the first connection assembly and the second connection assembly includes: a pivot member connected to the base in a lever arrangement, wherein a first end of the pivot member is coupled to at least one of the first driving mechanism or the second driving mechanism, wherein a second end of the pivot member is connected to the support surface, wherein actuation of at least one of the first driving mechanism or the second driving mechanism causes the pivot member to pivot about an axis of rotation defined by the connection of the pivot member to the base, wherein the pivoting of the pivot member causes the rotation and vertical translation of the support surface with respect to the base.
 28. The patient support apparatus of claim 27, wherein each of the first connection assembly and the second connection assembly is connected to the support surface by a slider connected to an underside of the support surface, wherein each of the first connection assembly and the second connection assembly further comprise a linear guide block connected to the second end of the pivot member, wherein the linear guide block is at least one of movably coupled to the slider or configured to move linearly along a longitudinal axis of the slider.
 29. (canceled)
 30. The patient support surface of claim 28, wherein the linear guide block is free in rotation about the slider, and wherein the axis of rotation of the linear guide block is a longitudinal axis of the slider. 31-32. (canceled)
 33. A radiotherapy apparatus comprising: a patient support surface, the patient support surface including: a support surface: a base: a first connection assembly connecting the support surface and the base, the first connection assembly being connected to the support surface at a first connection point, wherein the first connection assembly is coupled to a first driving mechanism configured to effect translation of the first connection point in a substantially vertical direction; a second connection assembly connecting the support surface and the base, the second connection assembly being connected to the support surface at a second connection point, wherein the second connection assembly is coupled to a second driving mechanism configured to effect translation of the second connection point in the substantially vertical direction; a third connection assembly connecting the support surface and the base. the third connection assembly being connected to the support surface at a third connection point, wherein the third connection assembly is coupled to a third driving mechanism configured to effect translation of the third connection point in the substantially vertical direction, and a processor configured to control the first driving mechanism, the second driving mechanism, and the third driving mechanism to at least one of rotate or vertically translate the support surface during treatment of the patient; wherein the third connection assembly includes a pivot joint at the third connection point configured to enable relative rotation between the support surface and the base, and wherein the first driving mechanism, the second driving mechanism, and the third driving mechanisms are configured to be independently driven to provide the rotation or the vertical translation of the support surface with respect to the base. 